How can epicardial adipose tissue be detected?

Detection of Epicardial Fat Deposits

Epicardial adipose tissue (EAT) is best detected using cardiac CT imaging, which allows precise quantification and can be performed rapidly using automated deep learning algorithms on non-contrast calcium-scoring CT scans. 1

Primary Imaging Modalities

Computed Tomography (CT) - Gold Standard

CT is the preferred method for detecting and quantifying epicardial fat deposits, offering several advantages:

• Non-contrast calcium-scoring CT scans are sufficient for EAT measurement 1
• Automated deep learning algorithms can quantify EAT in approximately 1.6 seconds with performance equivalent to expert readers 1
• CT distinguishes adipose tissue using Hounsfield units (HU) ranging from -190 to -30 HU 2
• Single-slice measurements at the level of the left main coronary artery correlate highly with total EAT burden (r = 0.89) and can serve as a practical proxy 3

The deep learning approach provides high agreement with expert manual quantification (R = 0.974) without significant bias, making it suitable for routine cardiovascular risk assessment 1.

Magnetic Resonance Imaging (MRI)

MRI offers an alternative imaging approach:

• Can measure EAT confined to the atrioventricular groove (GEAT), which strongly correlates with total atrial EAT (r = 0.95) 4
• Provides additional tissue characterization through T1 relaxation measurements 4
• Limited by high cost and 30-minute scan duration for whole-body imaging 2
• Cannot accommodate patients with severe obesity 2

Transthoracic Echocardiography

Echocardiography represents the most accessible method:

• Measures EAT thickness (in millimeters) on the surface of the right ventricle 5, 6
• Preferred for routine clinical use due to easy availability and low cost 5
• Normal values typically <9 mm; elevated thickness ≥9 mm indicates increased cardiovascular risk 7
• Provides a simple, cost-effective preventive tool for cardiovascular health assessment 6

Practical Clinical Algorithm

For routine screening and risk assessment:

• Use transthoracic echocardiography to measure EAT thickness alongside the right ventricle 5
• Consider EAT thickness ≥9 mm as clinically significant 7

For precise quantification and research:

• Obtain non-contrast cardiac CT (calcium-scoring protocol) 1
• Apply automated deep learning software for rapid quantification 1
• Single-slice measurement at the left main coronary artery level provides adequate assessment 3

For comprehensive tissue characterization:

• Use cardiac MRI with measurement of atrioventricular groove adipose tissue 4
• Combine with T1 mapping and atrial strain assessment for metabolic phenotyping 4

Important Clinical Considerations

The choice of imaging modality depends on clinical context:

• Echocardiography is sufficient for initial screening and serial monitoring in most patients 5, 6
• CT is preferred when precise volumetric quantification is needed or when assessing coronary artery disease risk 1, 3
• MRI adds value when evaluating atrial cardiomyopathy or in patients with metabolic disorders 4

Common pitfall: While CT and MRI provide volumetric measurements (cm³), echocardiography measures thickness (mm). These are not directly interchangeable, though both correlate with cardiovascular risk 5, 7.

The radiation exposure from CT is minimal with calcium-scoring protocols, and the ability to use automated quantification makes it increasingly practical for clinical use 1. However, echocardiography remains the most cost-effective first-line approach for detecting increased epicardial fat deposits in routine practice 5, 6.